Geo Cachers have a motto, cache in and trash out.  Translation as you are traveling to a geo cache grab any trash you see on the way to clean up the place you are

Last weekend every cacher was asked to do this and here is an article from Wausau Daily Harold about Geo Cachers doign their part

http://www.wausaudailyherald.com/article/20090503/WDH0101/905030557/1981